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<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div>
        <p>点击下面的按钮，只要 i 小于 5 就一直循环代码块。</p>
        <button onclick="whlie()">点击这里</button>
        <p id="whlie"></p>
        <script>
            function whlie() {
                var x = "", i = 0;
                while (i < 5) {
                    x = x + "该数字为 " + i + "<br>";
                    i++;
                }
                document.getElementById("whlie").innerHTML = x;
            }
        </script>
    </div>
    <hr />
    <div>
        <script>
            cars = ["BMW", "Volvo", "Saab", "Ford"];
            var i = 0;
            while (cars[i]) {
                document.write(cars[i] + "<br>");
                i++;
            }
        </script>
    </div>
</body>

</html>